title: C4B deficiency in two siblings with IgA nephropathy.
abstract: The development of IgA nephropathy in first degree relatives is a well-described, yet relatively uncommon, occurrence. The association of a C4 isotype deficiency or partial deficiency of another complement protein has been previously documented for patients with IgA nephropathy. The present report describes a family in which two siblings and their father had biopsy-confirmed IgA nephropathy; both siblings were deficient for the C4B isotype. In addition, one of the biopsied siblings and a third sibling with microscopic hematuria but no renal biopsy apparently had a partial deficiency of the complement regulatory protein, I. The findings in this family may be compatible with the hypothesis that a C4 isotype deficiency and/or a partial deficiency of an individual complement protein allows clinical expression of IgA nephropathy in an individual with a genetic susceptibility for the disease.
authors.affiliation: Department of Pediatrics, University of Tennessee, Memphis.
authors.forename: R J
authors.initials: RJ
authors.lastname: Wyatt
authors.forename: P D
authors.initials: PD
authors.lastname: Schneider
authors.forename: C E
authors.initials: CE
authors.lastname: Alpers
authors.forename: E C
authors.initials: EC
authors.lastname: Hudson
authors.forename: B A
authors.initials: BA
authors.lastname: Julian
mesh_terms: D000293:Adolescent; D000328:Adult; D000347:Afibrinogenemia / Q000150:complications / Q000235:genetics; D015934:Complement C4a / Q000032:analysis / Q000235:genetics; D015935:Complement C4b / Q000172:deficiency*; D004587:Electrophoresis, Agar Gel; D005260:Female; D005922:Glomerulonephritis, IGA / Q000150:complications / Q000235:genetics / Q000276:immunology*; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010641:Phenotype
chemical_list: D015934:Complement C4a; D015935:Complement C4b